Weighing scale with ten times sensitivity increase

ABSTRACT

Disclosed herein is a weighing machine that will indicate weight in any weight system desired utilizing a single graduated scale. A beam is supported by a fulcrum on a stand. A weight pan is hung from the beam on one side of the fulcrum, and a slidable poise of variable weight is carried on the beam on the side opposite the weight pan. A graduated scale is affixed to the beam on the side opposite the weight pan and has its zero in the vertical plane of the fulcrum. The mass and center of gravity of the beam on one side are adjustable to balance with the other side while the poise is at zero and in the vertical plane of the fulcrum. This enables poises corresponding to other weight systems to be attached to the beam without disturbing its equilibrium. Consequently the scale will indicate whatever units the poise is designed for.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 561,043, filed Mar. 24, 1975.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to weighing machines and in particularto a beam weighing machine that will indicate weight in multiple weightsystems with a single graduated scale.

2. Description of the Prior Art

Beam type weighing machines wherein a beam is supported on a fulcrumwith the object to be weighed hung from one side, and a poise slidableon a graduated scale fixed to the other side are well known. To measurethe weight of an object on this type of weighing machine, initially thebeam is balanced while the poise is at zero on the scale, then theobject is hung on the load side and the poise advanced along the scaleuntil the beam balances. The graduations and indicia on the scale willindicate weight in whatever system the beam is designed for.

In prior art machines of this type, zero of the scale is to one side ofthe fulcrum, therefore, changing the weight of the poise places themachine out of balance. Before it would properly indicate weight inanother weight system corresponding to another poise, the beam wouldhave to be balanced again to account for the different weight of poise.Because of the different poise weight, this may not be possible.

There is a prior art weighing machine that will weigh in two systems andis disclosed in U.S. Pat. No. 3,506,078 D. M. Homs on Apr. 14, 1970.However, this machine utilizes two separate graduated scales, eachhaving graduations and indicia to correspond to a different weightsystem.

SUMMARY OF THE INVENTION

One of the objects of this invention is to provide an improved beam typeweighing machine. Another object of this invention is to provide animproved beam type weighing machine that will indicate weight inmultiple systems on a single graduated scale merely by changing theweight of the poise and without further adjustment.

In accordance with these objects, the weighing machine is provided witha beam which contains a slidable poise that may be positioned directlyin the vertical plane of the fulcrum. One side of the beam is adjustableso that the beam will balance while the poise is directly in thevertical plane of the fulcrum. Consequently, varying the weight of thepoise to correspond to different weight systems does not disturb thebeam once balanced. The graduated scale has its zero in the verticalplane of the fulcrum and will read in whatever system the particularpoise is calabrated for.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a weighing machine in accordance withthis invention.

FIG. 2 is a top elevational view of the weighing machine shown in FIG.1.

FIG. 3 is a partial top elevational view of a prior art beamconstruction for a platform weighing machine.

FIG. 4 is a partial elevational view of the beam construction shown inFIG. 3.

FIG. 5 is a partial top elevational view of a beam constructionconstructed in accordance with this invention for a platform weighingmachine.

FIG. 6 is a partial elevational front view of the beam construction ofFIG. 5.

FIG. 7 is a front elevational view of a metric poise adapted to beattached to the pounds of FIGS. 5 and 6.

FIG. 8 is a side elevational view of the poise of FIG. 7.

FIG. 9 is a side elevational view of the pounds poise of FIGS. 5 and 6shown detached from the beam construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIGS. 1 and 2, a beam type weighing machine isshown including its stand. The stand comprises a rectangular base 11 ofwood or metal having set screws 13 spaced for leveling.

Part of the stand is an elongated member, as metal tube 15, extendingupwardly therefrom. The tube 15 is bent at an obtuse angle at a selecteddistance from base 11, forming arm 17. Arm 17 is laterally disposedgenerally along the length of the base 11 and is at an acute angle withrespect to base 11. Transversely piercing arm 17 toward the end of thebent portion is a pin 19, held in position by screw 21. Each end of pin19 extends beyond arm 17, and elongated metal loops 23 slipped looselyover each of these ends. At the end of arm 17, a bracket 25 having aslot 27 and face 29, with horizontal lines to indicate balance, issecured to arm 17 and extends downwardly.

At the bottom of loops 23 a fulcrum 31, comprising a V-shaped knife edgein a selected vertical plane, is carried with its edge transverse to thearm 17. The top of the fulcrum 31 is secured to a metal plate 33 that isattached to a lever 35. Lever 35 is a flat metal plate extendingperpendicularly to the longitudinal axis of the fulcrum 31 through slot27 and terminating at a selected distance beyond bracket 25. A secondfulcrum, as V-shaped knife edge 37, extends from lever 35 at a selecteddistance from fulcrum 31 and slightly below. A third fulcrum, asV-shaped knife edge 39, extends from lever 35 at a point 10 times thedistance from knife edge 37 to fulcrum 31. Knife edge 39 fits within anoblong hole (not shown) in lever 35 and set screws 40 position and lockknife edge 39 precisely at the proper distance. The longitudinal axis ofknife edges 37, 39 are perpendicular to the axis of the lever andparallel to the longitudinal axis of fulcrum 31. Elongated loops 41, 43fit loosely over each knife edge 37, 39 similar to loop 23. Hangingmeans, as hooks 45, 47, are suspended from each loop 41, 43. A weightcarriage, illustrated as weight pan 49 suspended by bail 51, hangsinterchangeably from hooks 45 or 47. A tare poise 53, equal to theweight of the weight pan 49 and bail 51, is suspended interchangeablyfrom either of the hooks 45 or 47.

A bracket 55 is secured to lever 35 between knife edge 37 and fulcrum31, and extends in a vertical plane perpendicular to lever 35. On oneside of the bracket 55, a balance adjusting means, comprising a threadedscrew 57 and cylindrical weight 59 threaded thereon, is secured to thebracket 55. Threaded screw 57 is aligned generally parallel to thelongitudinal axis of lever 35 and extends in the opposite direction. Onthe other side of the bracket 55, a threaded rod 61 is attached througha hole in the bracket 55, the hole being slightly larger than the rod 61so that the rod is rotatable. Both the threaded screw 57 with its weight59 and the threaded rod 61 extend parallel to the lever 35 and in theopposite direction from the bracket 55. Tube 15 with its arm 17 extendsbetween the threaded rod 61 and cylindrical weight 59.

a graduated scale 63 is fixed to bracket 55 and is aligned directlybelow and parallel to rod 61, and is laterally disposed from lever 35.Scale 63 is notched or fixed on a metal plate and comprises indiciaindicating slightly more than ten major divisions, which arerespectively divided into ten smaller divisions. The zero of the scaleis directly below the knife edge of fulcrum 31, thus in the verticalplane of the fulcrum. One major division is the length of the distancefrom knife edge 37 to fulcrum 31. Ten threads of threaded rod 61correspond to one major division of scale 63.

A graduated drum 65 is secured to the end of the threaded rod 61 and isadjacent the end of scale 63. Drum 65 is graduated into ten majordivisions, each containing ten smaller divisions. One full rotation ofthe drum corresponds to one small division of scale 63.

A hanging means, as hook 67, is located slightly beyond the tenth majordivision of scale 63. A weight 69, shown detached, is designed forattachment to hook 67 for doubling the capacity of the weighing machine.

A hanger 71, extending over scale 63 and slidably carried by threadedrod 61, comprises a flat plate having an aperture, designated by numeral73, for viewing the graduated scale, and hanging means, as hole 75, forhanging a poise 77 by its hook 79. The hanger 71 rests on a pin 80 (FIG.2) which is part of a slider 82 which rests in the threads of the rod61. Hanger 71 may be lifted up slightly and manually moved along the rod61, or may be advanced along the threads by rotating rod 61 by means ofdrum 65. One full rotation of drum 65 advances hanger 71 one smalldivision.

In operation, the combination comprising the lever 35, threaded rod 61,scale 63, and balance adjusting means serve as the beam for the weighingmachine. Before the object to be measured is placed in the weight pan49, the poise 77 must be at zero in the vertical plane of fulcrum 31 andthe beam must be at equilibrium. At equilibrium the masses on eitherside of the fulcrum are balanced by adjusting weight 59 so that theresultant center of gravity of the beam passes through the plane of thefulcrum 31. At this point, the moment on one side of the beam equals themoment on the other side of the beam. While achieving initialequilibrium, the weight pan 49 may be either in the gross mode, asillustrated, with the pan 49 hanging from knife edge 37 and tare poisefrom knife edge 39, or in the sensitive mode with the weight pan 49hanging from knife edge 39 and tare poise 53 from knife edge 37.

Once initial equilibrium is achieved, the poise 77 and hanger 71, beingat zero and in the vertical plane of the fulcrum 31, do not effect thebeam balance. Poise 77 may be removed entirely and another weight poisesubstituted without disturbing the equilibrium. Consequently hanger 71serves as a conversion means to other weight systems, since it allowsthe poise 77 to be detached and others to be placed thereon.

After initial equilibrium is achieved, the object to be weighed,illustrated as numeral 81, is placed in the weight pan 49. A poise 77corresponding to whatever weight system desired is hung on the hanger 71and advanced forward along scale 63 manually and by rotating drum 65until balance is achieved. With the weighing machine in the gross mode,as illustrated, the indicia of the scale will read directly in theweight system of the poise.

In the preferred embodiment, the weight of the poise 77 and hanger 71equal one basic unit of whatever weight system is being used. Forexample, if it is desired to weigh in kilograms, poise 77 is constructedto weigh one kilogram including its hook 79 and the hanger 71.Consequently, if the object 81 weighs one kilogram, the beam will be atbalance while the poise is hanging at unit one on the scale 63. If thesame object 81 is desired to be measured in pounds, poise 83, whoseweight combined with hanger 71 equals one pound, is substituted forpoise 77. The beam will balance again when poise 83 is advanced to 2.2and the drum 65 rotated to four and six-tenths small divisions, therebyindicating 2.2046. Any poise weight may be utilized so long as it doesnot exceed the beam and stand strength. While in the gross mode, theindicia of scale 63 will indicate weight according to the indiciareading multiplied by the poise and hanger 71 weight.

In the sensitive mode, weight pan 49 changes position with tare poise53. Because the distance to the fulcrum 31 is thereby increased tentimes, the sensitivity is ten times greater. A one pound weight in thepan must be balanced by pound poise 83 at indicia ten on scale 63. Theindicia of scale 63 indicate weight in this mode as the readingmultiplied by one-tenth times the weight of the poise and hanger 71weight.

The capacity of the weighing maching may also be multiplied to an extentdepending on beam strength. Weight 69 is designed to double the capacityin the pound gross mode. Weight 69 is hung from hook 67, which isslightly past the ten indicia in order to prevent the weight 69 frominterferring with poise 83 movement. To account for the extra distanceof the moment arm, weight 69 is slightly less than one pound. To operatein this mode, the doubling weight 69 is attached after the scale hasbeen balanced in initial equilibrium through adjusting weight 59. Withthe doubling weight 69 attached and poise 83 at zero, a ten pound objectin the pan will balance the beam. Accordingly the indicia of the scaleindicate weight as ten plus the indicia unit; i.e. indicia one indicates11 pounds.

The principle of this invention of constructing a beam type weighingmachine so that the poise and scale zero may be placed in the verticalplane of the fulcrum may be applied to existing weighing machines. FIGS.3 and 4 indicate the beam construction of a conventional platformweighing machine commonly used in hospitals for measuring people'sweight.

The conventional machine of this type includes a beam supported on aV-shaped knife edge fulcrum 85, which pivotally engages a linkage 87attached to a stand (not shown). The beam comprises a lever 89 on oneside of fulcrum 85, which has adjusting means illustrated as weight 91,Weight 91 is threaded on a rod 93, which is rotatably attached to thelever 89 so that the weight may be moved along the longitudinal axis oflever 89.

A second fulcrum, as knife edge 95, extends perpendicularly throughlever 89. This knife edge 95 is linked by a rod 97 to a weight carriage,as a platform (not shown), for placing objects to be weighed. On theside of the beam opposite the fulcrum 85, a graduated scale 99 is fixed.In the prior art, the zero is at a selected distance to one side offulcrum 85. A poise 101 fits slidably on the scale 99. This prior artweighing machine will indicate weight in only one weight system.

In order to modify this type of beam weighing machine to indicate weightin multiple weight systems, modifications must be made as shown as inFIGS. 5 through 9. As illustrated in FIGS. 5 and 6, the beam isidentical with respect to the fulcrum 85, lever 89, knife edge 95,linkage 87, 97, and adjusting means. However the scale 99 and poise 101are modified as shown by the numerals 103 and 105 respectively in orderto allow the poise 105 to be placed in the vertical plane of the fulcrum85, and to place the zero of scale 103 in the vertical plane of fulcrum85. Also poise 105 is modified so that its weight can vary, serving asconversion means to change to other weight systems.

In the improved beam construction, a bracket 107 is attached to lever 89and extends in a vertical plane perpendicularly to lever 89. Asillustrated bracket 107 is positioned between knife edge 95 and rod 93,and must be at a sufficient distance from fulcrum 85 so that the centerof gravity of poise 105 can be placed in the vertical plane of fulcrum85. Lever 89 terminates slightly adjacent fulcrum 85.

Scale 103 is offset from the vertical plane of lever 89 and affixed tobracket 107 so that there is a sufficient clearance between fulcrum 85and scale 103 for poise 105 to slide between. Scale 103 is alignedgenerally parallel to the lever 89 and extends in the oppositedirection, thereby comprising one-half of the beam.

Poise 105 contains a longitudinal rectangular passage designated asnumeral 109, so that it may be placed on and slid along scale 103. Thereis also an aperture, designated by numeral 111, for viewing indicia onscale 103. Poise 105 as illustrated in FIGS. 6 and 9, containsconversion means to weigh in two systems, illustrated as pounds andkilograms. Conversion means comprises means for attaching a secondpoise, as ledges 113, extending horizonally across faces 115 of poise105. Ledges 113 mate and lock by notch 118 with corresponding lips 117on a second poise 119. Poise 119 hangs on ledges 113 of poise 105, andthe weight of poise 119 is sufficient to convert the system to metric.The weight of both poise 105 and 119 depends upon the distance betweenfulcrum 85 and knife edge 95, and the scale desired.

To operate the improved weighing machine in the pound mode, the beammust initially be balanced while the poise is at zero. The object to beweighed is placed on the platform (not shown) and poise 105 slid alongscale 103 until balance is once again achieved. Scale 103 will readdirectly in pounds. To operate the improved weighing machine in thekilogram mode, it is not necessary to again achieve equilibrium sincethe poise weight has no effect on this. Poise 119 is merely hung onpoise 105 and the combination slid along scale 103 until balance againachieved. Scale 103 will directly read in kilograms.

Existing beam construction may be modified accordingly, or a beamconstructed in accordance with this invention may be fitted to existingweighing machines.

It should be apparent from the foregoing description that an inventionhaving significant advantages has been provided. Weight may be measuredin an indefinite number of weight systems without the need forconversion tables. The single graduated scale is used for all of thedifferent systems, avoiding the confusion of different indicia on onescale, and also avoiding the need for multiple scales. Weighing machinesconstructed according to this principle add flexability yet do not addcomplexity or expense.

While this invention has been shown in only two of its forms, it shouldbe apparent to those skilled in the art that it is not so limited but issusceptible to various changes and modifications without departing fromthe spirit thereof, and it may be adapted to other beam type weighingmachines of configurations not shown.

I claim:
 1. A weighing machine comprising:a stand; a fulcrum carried bythe stand in a selected vertical plane; a lever carried by and locatedbelow the fulcrum; a weight pan carried by the lever on a first hangingmeans; a tare poise equal to the weight of the pan carried by the leveron a second hanging means, said second hanging means being located at aneven multiple of the distance from the fulcrum to the first hangingmeans, whereby exchanging the tare poise with the weight pan changessensitivity by an even factor; a graduated scale secured to the lever bya bracket, said scale being adjacent said lever in a different plane andlaterally disposed generally parallel to the longitudinal axis of thelever, said scale having its zero in the vertical plane of the fulcrum;a rotatable rod secured to the bracket and extending parallel to thescale, said rod containing a selected number of threads for each majordivision of the scale; a detachable poise carried on the rod by ahanger, said hanger capable of being manually slid along the rod andalso mating with the threads of the rod for advancement by rotating therod; an adjusting weight attached to the lever for adjusting theresultant moment on one side of the fulcrum to equal the resultantmoment on the other side of the fulcrum while the poise is at zero andin the vertical plane of the fulcrum.
 2. The weighing machine as definedby claim 1 wherein the stand comprises a base and an elongated memberattached to the base extending upwardly and bending laterally above andalong the lever, the fulcrum being carried by the elongated member. 3.The weighing machine as defined by claim 1 wherein a drum is affixed tothe rod, said drum having graduated indicia to indicate one full turn,with one full turn corresponding to one small division on the scale.